The present invention relates generally to a continuously adjustable rotation device, and more particularly to a rotation device that is easy to assemble and can perform precise rotational movements, thereby improving the rotational alignment and lowering the manufacturing cost thereof. The continuously adjustable rotation device of the present invention is applicable to many products that require the performance of rotational motions.
Rotational mechanism is normally applied to products that perform single directional or double directional rotations. For example, the rotational mechanism is commonly seen in a ratchet wrench, a shaft for adjusting the illuminating angles of a lamp, a positioning shaft for adjusting the angle formed between a seat and a seat back, etc. Some conventional rotational mechanisms employ a ratchet wheel or a ratchet to incorporate with a positioning element. Other rotational mechanisms employ the incorporation between a concave portion and a protrusive point, or the incorporation between an elastic element and steel balls, so as to obtain a single directional or a double directional rotational operation and positioning. However, these rotational mechanisms are restricted to sectional positioning. In other words, only at certain rotational angles can the rotational mechanism be securely positioned. One can not continuously adjust the rotational motion and position the rotational mechanism at any desirable rotated angle.
One possible solution to the aforementioned drawbacks is disclosed in the Published Taiwanese New Utility Model Patent No. 527989, entitled “Continuously Adjustable Ratchet Wrench.” In this conventional art, the continuously adjustable ratchet wrench includes a slanted continuously adjustable disc base disposed at the bottom portion of a wrench body. The slanted frictional surface faces upward, which contacts a continuously adjustable rotational mechanism for transmission of force. The continuously adjustable rotational mechanism includes a spherical disc, a slanted continuously adjustable disc, and a combining shaft. The combining shaft is thrust into the spherical disc and the slanted continuously adjustable disc, and is combined with the slanted continuously adjustable disc base. Further, a C-shaped buckle and a pushing rod mechanism are employed to select the rotation direction and to control the rotation. When one rotates the combining shaft to an angle, the spherical disc, the slanted continuously adjustable disc and the slanted continuously adjustable disc base perform frictional rotational motion with the combining shaft along the contact surface. In addition, the pushing rod and the elastic element of pushing rod mechanism are pushed to move backward in response to the compression of the slanted continuously adjustable disc. Furthermore, the pushing rod of the pushing rod mechanism is pushed outward due to the elastic force from the elastic element after the combining shaft is rotated to a certain angle, thereby tightly pushing the slanted continuously adjustable disc to securely position the rotated angle.
However, the fabrication of the slanted continuously adjustable disc base and the slanted continuously adjustable rotational mechanism requires the use of high precision equipment and highly accurate alignment assembly process. Therefore, the yield of manufacturing is significantly lower than expected and the cost thereof is much higher. Moreover, the rotational operation can not guarantee that the slanted surfaces are properly contacted with each other.